The world's newest snake species has menacing-looking yellow and black scales, dull green eyes and two spiky horns – and it's named after a seven-year-old girl.

Matilda's horned viper was discovered in a small patch of south-west Tanzania about two years ago. In December, it was introduced as the world's newest known snake species in an issue of the Zootaxa journal.

Tim Davenport, the director of the Wildlife Conservation Society (WCS) in Tanzania, was on the three-person team that discovered the viper and, thanks to his daughter, it will always have a family namesake.

"My daughter, who was five at the time, became fascinated by it and used to love spending time watching it and helping us look after it," Davenport said on Wednesday. "We called it Matilda's viper at that stage … and then the name stuck."

Only three new vipers have been discovered across Africa in the past three decades. To avoid the attention of trophy hunters, the WCS is not revealing the snake's location.

Davenport said he is not sure how many of the vipers live in the wild because snake counts are tricky. Twelve live in captivity, and a breeding plan is being carried out.

He said that, while many people fear snakes, most are harmless and help keep rodent numbers down.

Matilda's horned viper can grow to 65cm or bigger, he said, adding: "This particular animal looks fierce and probably is venomous," Davenport, a Briton who has lived in Tanzania for 12 years, told the Associated Press. "However, it is actually a very calm animal and not at all aggressive. I have handled one on a number of occasions."

The WCS runs the Bronx and Central Park zoos in New York, and Davenport said it would be a "great option" to showcase the new horned viper at one of those locations. However, he added that nothing had yet been decided.